In recent years, many scientists and researchers have shown considerable interest in biomass-derived molecules, known as platform molecules or building blocks.
Typical examples of such platform molecules may include 5-hydroxymethyl-2-furfural (hereinafter referred to as HMF), which is recently receiving attention as a biomass-derived furan-based compound, and 2,5-furandicarboxylic acid (hereinafter referred to as FDCA), produced by an oxidation reaction on HMF.
In particular, FDCA, which is a platform molecule, is structurally similar to terephthalic acid, serving as a raw material of polyester, which is a typical polymer, and may thus be used as an alternative to terephthalic acid. Furthermore, an FDCA-based polymer, for example, poly(ethylene-2,5-furandicarboxylate) (PEF), has also been studied as an alternative polymer to polyethylene terephthalate (PET).
U.S. Patent Publication (US 2012/0059178 A1) discloses a process for oxidation of furan aldehyde such as HMF using a Co/Mn binary catalyst system. Here, the use of Co/Mn and MEK (methyl ethyl ketone) as a catalyst causes selective oxidation into DFF, and the use of Co/Mn and bromide as a catalyst causes selective oxidation into 2,5-furandicarboxylic acid (hereinafter referred to as FDCA).
Also, U.S. Patent Publication (US 2011/0092720 A1) discloses a method of preparing FDCA, which produces FDCA having high purity at high yield, comprising bringing HMF into contact with an oxidizing agent in an organic acid (solvent) in the presence of bromine and a metal catalyst and allowing HMF to react with the oxidizing agent. These methods allow the reaction to proceed while removing the water produced by the reaction, and the yield of FDCA is about 62%.
However, the above methods are problematic because the preparation process is complicated or high temperature and pressure have to be used, the purity and productivity of final products are low, and, upon preparation of FDCA, oxidation does not completely occur, and thus byproducts other than FDCA, for example, 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 5-formyl-2-furancarboxylic acid (FFCA), 2,5-diformylfuran (DFF), and the like, may be generated. Hence, improvements in processes for selective oxidation of FDCA are continually required.